In recent years, fluoroaluminosilicate ("FAS") glass cements, also known as "glass ionomer cements", have become widely used in dentistry. They are fluoride-releasing and therefore cariostatic. However, they are also relatively fragile, as manifested by their low diametral tensile strength ("DTS") and low fracture toughness ("K.sub.1c "). Glass ionomer cements are widely accepted for low stress applications such as liners and bases, but are prone to early failure in restorative applications, core build-ups and other high stress applications. This has tended to limit clinical use of these otherwise meritorious cements.
U.S. Pat. No. 5,063,257 describes glass ionomer cements containing a polymerizable unsaturated organic compound. In several examples of the '257 patent (e.g., examples 6-8 and 14-16), the fluoroaluminosilicate glass is treated with an anhydrous alcoholic solution of an ethylenically-unsaturated alkoxysilane. The resultant silane-coated glass is dried and later mixed with a polyacrylic acid and a methacrylate monomer. The '257 patent mentions but does not exemplify treating the glass with unsaturated carboxylic acids such as methacrylic acid, acrylic acid and maleic acid.
U.S. Pat. No. 4,250,277 describes a cement made from a treated aluminoborate glass. The treatment involves washing the glass with ammonium phosphate, in order to extend the setting time of the cement.
U.S. Pat. No. 4,376,835 describes a calcium aluminum fluorosilicate glass that has been treated with an acid. The treatment is said to reduce water sensitivity and extend setting time.
U.S. Pat. No. 4,652,593 describes a metal oxide cement containing a mixture of calcium oxide and aluminum oxide. The oxide powders are coated with a water-soluble high molecular weight substance. The coating is said to increase crushing strength, hydrophilicity and working time, and to decrease solubility.
U.S. Pat. No. 4,808,288 describes glass ionomer cement powders made by vigorous comminution of a glass and a carboxylic acid. The powders contain carboxylate groups.
European Published Patent Application 0 323 120 and U.S. Pat. No. 4,872,936 describe photocurable cements. The '936 patent describes silane-treating an optional added filler (e.g., microfine silica) but not a glass ionomer powder.
U.S. Pat. No. 4,673,354 describes silanol solutions that can be used to prime dental porcelains and dental alloys.